T3 is 10 times more potent than T4, and can have very significant and rapid effects on heart rate and blood pressure. Whereas T3 is often well tolerated in younger patients taking the correct dose, older patients with known or suspected heart disease should be extremely cautious about taking significant amounts of T3.
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1. J Clin Endocrinol Metab. 2014 Oct;99(10 3782-9. doi: 10.1210/jc.2013-4454. Epub 2014 Jul 16. The effect of long-term thyroid-stimulating hormone suppressive).
Experimental studies in mice lacking either the TR-alpha or TR-beta receptor suggest bone loss is mediated by TR-alpha 6. Thus, thyroid hormone may affect bone calcium metabolism either by a direct action on osteoclasts, or by acting on osteoblasts which in turn mediate osteoclastic bone resorption 7.
INTRODUCTION The adverse effects of hyperthyroidism on the skeleton were known before the advent of satisfactory treatment for hyperthyroidism. One of the first reports of hyperthyroid bone disease was in 1891 when von Recklinghausen described the "worm eaten" appearance of the long bones of a young woman who died from hyperthyroidism 1.
Some patients sensitive to and concerned about this issue who feel strongly about the need for exogenous T3 are taking thyroid extract, as available from companies such as Armour Pharmaceuticals, which contains a combination of both T4 and T3.
The adverse effects of hyperthyroidism on the skeleton were known before the advent of satisfactory treatment for hyperthyroidism. One of the first reports of.
Very little of the more biologically potent T3 is derived from our thyroid gland. However, our body generates its own T3 from T4 by removing a single iodine molecule, using an enzyme called a deiodinase.
Thyroid hormone directly stimulates bone resorption in organ culture 2. This action may be mediated by a nuclear triiodothyronine (T3) receptor which has been found in rat and human osteoblast cell lines 3-5 and in osteoclasts derived from an osteoclastoma 5.
TSH Suppression Benefits and Adverse Effects by Jeffrey Dach MD. At a recent medical meeting I attended, the danger of TSH suppression was mentioned.
Some thyroid extract preparations may not always be as standardized, compared to simple thyroxine tablets, with respect to the relative amounts of T4 and T3 in each preparation. Furthermore, taking T3, ideally in physiologically normal amounts but sometimes inadvertently in excess is not always without risk.
These changes in bone metabolism are associated with negative calcium balance, hypercalciuria and, rarely, hypercalcemia (see below). Literature review current through: Feb 2016. This topic last updated: Mon Jul 06 00:00:The content on the UpToDate website is not intended nor recommended as a substitute for medical advice, diagnosis, or treatment.
With the introduction of antithyroid drugs and radioiodine in the 1940s, clinically apparent hyperthyroid bone disease became less common. However, bone density measurements during the last decade have demonstrated that bone loss is common in patients with overt hyperthyroidism and to a lesser extent in those with subclinical hyperthyroidism, whether caused by nodular goiter or.
Endocr Res. 2009;34(3 80-9. There is correlative evidence in the psychiatric literature that depressed patients with lower levels of thyroid hormone may take longer to respond to anti-depressant medication. Slower Treatment Response in Bipolar Depression Predicted by Lower Pretreatment Thyroid Function.
There was no difference in any clinical endpoint assessed in the different treatment groups with or without T3, as described in Substitution of liothyronine at a 1:5 ratio for a portion of levothyroxine: effect on fatigue, symptoms of depression, and working memory versus treatment with levothyroxine alone.
A common finding in some, nut not all of these studies is that patients taking some form of T3 supplement feel better, in some subjective or objective measurements of mood or cognitive function, than those taking T4 alone.
J Clin Endocrinol Metab. 2011 Nov;96(11 3466-74 Nevertheless, many of these studies are small, not well controlled, often non-randomized, and hence may not be valid and generally applicable to the majority of patients with hypothyroidism as is partly the case for the study described in.
Endocr Pract. 2005 Jul- Aug; 11(4 223-33 Furthermore, a randomized control trial of T4 alone vs. T4 plus T3 for 12 weeks again failed to show any significant improvements in mood or cognitive function, as outlined in Replacement therapy with levothyroxine plus triiodothyronine (bioavailable molar ratio 14 : 1) is not superior to thyroxine alone.